libgit: construct the git Config before getting the TLF handle
libgit: construct the git Config before getting the TLF handle

Otherwise, a journal will be created for the TLF under the normal
Config, and later journal calls on the git Config will fail due to a
missing handle.

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client